The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Food waste disposers are known in the art, such as the food waste disposers disclosed in U.S. Pat. No. 6,007,006 for a “Food Waste Disposer” and 6,439,487 for “Grinding Mechanism for a Food Waste Disposer and Method of Making the Grinding Mechanism,” the entire disclosures of which are incorporated herein by reference.
FIG. 1 depicts a vertical cross-section of a typical food waste disposer 100. The disposer may be mounted in a well-known manner in the drain opening of a sink using mounting members of the type disclosed in U.S. Pat. No. 3,025,007, which is owned by the assignee of the present application, and incorporated herein by reference in its entirety. The disposer includes an upper food conveying section 112, a lower motor section 114, and a central grinding section 116 disposed between the food conveying section 112 and the motor section 114. The food conveying section 112 includes an injection-molded plastic housing 118 that forms an inlet 120 at its upper end for receiving food waste and water. The housing 118 also forms a dishwasher inlet 121 for passing water discharged from a dishwasher (not shown). As used herein, a “dishwasher inlet” is a member such as a fitting to which an outlet of a dishwasher can be coupled such as by hose, and provides a fluid passageway into the food waste disposer through which waster discharged from the dishwasher can flow into the food waste disposer. The food conveying section 112 conveys the food waste to the central grinding section 116. The motor section 114 includes an induction motor 122 imparting rotational movement to a motor shaft 124. The motor 122 is enclosed within a motor housing 126 having a stamped metal upper end frame 128, a stamped metal lower end frame 130, and a bent metal stator band 132 extending between the upper and lower end frames 128 and 130.
The grinding section 116 includes a grinding mechanism having a circular grinding plate or disc 134, a pair of lugs 136, and a stationary shredder ring 138. The plate 134 is mounted to the motor shaft 124 of the motor section 114 and rotates with motor shaft 124. The lugs 136 are fastened to the plate 134 but are free to rotate relative to the plate 134. The grinding section 116 includes an injection-molded plastic housing 140 integrally formed with the injection-molded upper housing 118 of the food conveying section 112. The integrated injection-molded plastic housings 118 and 140 form a unitary plastic enclosure. The enclosure is fastened to the lower end frame 130 by a plurality of bolts 141 having self-tapping threads.
To prevent the food waste from leaking between the housing 140 and the upper end frame 128, a sealant bead 143 is applied therebetween. The sealant bead 143 is preferably composed of a tacky, malleable material that fills any voids between the housing 140 and the upper end frame 128 and tempers any irregularities in the opposing surfaces of the housing 140 and the upper end frame 128. Some suitable malleable materials for the sealant bead 143 include butyl sealant, silicone sealant, and epoxy.
The housing 140 of the grinding section 116 encompasses the grinding mechanism. The shredder ring 138, which includes a plurality of spaced teeth 142, is fixedly attached to an inner surface of the housing 140 by an interference fit and is preferably composed of galvanized steel. Since the housing 140 is composed of injection-molded plastic instead of die-cast metal, the housing 140 is resistant to corrosion from the shredder ring 138. In the operation of the food waste disposer, the food waste delivered by the food conveying section 112 to the grinding section 116 is forced by the lugs 136 on the plate 134 against the teeth 142 of the shredder ring 138. The sharp edges of the teeth 142 grind or comminute the food waste into particulate matter sufficiently small to pass from above the plate 134 to below the plate 134 via gaps between the teeth 142 outside the periphery of the plate 134. Due to gravity, the particulate matter that passes through the gaps between the teeth 142 drops onto the upper end frame 128 and, along with water injected into the disposer 100 via the inlet 120, is discharged through a discharge outlet 144 into a tailpipe 146. To direct the mixture of particulate matter and water toward the discharge outlet 144, the upper end frame 128 is sloped downward toward its periphery.
The discharge outlet 144 is formed by the plastic housing 140 and has a threaded outer surface. The threaded outer surface of the discharge outlet 144 allows the tailpipe 146 to be connected to the discharge outlet 144 using an off-the-shelf plumbing nut 148.
The stamped metal upper end frame 128 separates the grinding section 116 from the motor 122. To promote concentricity of the motor shaft 124 relative to the stator band 132 and of the plate 134 relative to the shredder ring 138, a peripheral lip of the upper end frame 128 is secured between the plastic housing 140 and the stator band 132. The upper end frame 128 dissipates the heat generated by the motor 122, prevents particulate matter and water from contacting the motor 122, and directs the mixture of particulate matter and water to the discharge outlet 144.
To align the motor shaft 124 relative to the stator band 132 and, at the same time, permit rotation of the motor shaft 124 relative to the upper end frame 128, the upper end frame 128 forms a central bearing pocket 150 supporting a powdered metal spherical bearing 152. The spherical bearing 152 encompasses the motor shaft 124 and is retained in the bearing pocket 150 by a steel bearing retainer 154. To evenly distribute downward loads created by the grinding mechanism onto the bearing 152, a thrust washer 156 encompasses the motor shaft 124 and is positioned immediately above the spherical bearing 152. A steel sleeve 158 encompasses the motor shaft 124, is positioned immediately above the thrust washer 156, and is surrounded by a spring-loaded rubber seal 160. Finally, the steel sleeve 158 is covered by a steel cap 162 for keeping out debris.
The injection-molded plastic housings 118 and 140 are composed of a plastic material that exhibits impact resistance, heat resistance, and corrosion resistance. Some suitable plastic materials for the housings include acrylonitrile butadiene styrene (ABS), polyvinyl chloride (PVC), polyester, and polyphenylene sulfide. The housings 118 and 140 preferably have a wall thickness ranging from about 0.120 inch to about 0.160 inch. In a preferred embodiment, the housings 118 and 140 have a wall thickness of about 0.140 inch. To enhance the structural rigidity of the housing 140, the housing 140 may be provided with a plurality of stiffening ribs (not shown).
The upper end frame 128 is preferably composed of stamped metal that is capable of conducting the heat generated by the motor 122 to the water flowing through the disposer and is sufficiently rigid to withstand downward loading forces applied by the plate 134 of the grinding mechanism. Some suitable metals include double-sided galvanized cold-rolled steel, cold-rolled steel, stainless steel, and other types of steel. Alternatively, the upper end frame 128 may be composed of a structurally rigid plastic material capable of dissipating the heat generated by the motor 122. When composed of stamped metal, the upper end frame 128 preferably has a wall thickness ranging from about 0.040 inch to about 0.060 thick. In a preferred embodiment, the upper end frame 128 is composed of double-sided galvanized cold-rolled steel and has a wall thickness of about 0.047 inch.
Dishwasher inlet 121 is extended laterally into grind chamber 164 of the disposer body in order to pass certain agency tests included in ASSE 1008. The grind chamber 164 is defined by housings 118 and 140. The approving agencies, such as ASSE and UL, require a disposer to pass, among others, a pumping test prior to the disposer being marketed. The pumping test can typically be passed if the dishwasher inlet extends into the grind chamber.
In a disposer having the prior art dishwasher inlet 121, the dishwasher inlet including the portion that extends into the grind chamber 164 is molded integrally as part of housing 118. This dishwasher inlet structure causes difficulty in the molding of an anti-vibration mount which food waste disposers often have. The anti-vibration mount is an annular mount molded of a resilient material around inlet 120 of housing 118. Examples of such anti-vibration mounts are disclosed in U.S. Pat. No. 7,021,574 issued Apr. 4, 2006 for “Overmolded Vibration Isolation Gasket for Mounting Food Waste Disposer to Sink,” the entire disclosure of which is incorporated herein by reference.
In some cases, the molding of the anti-vibration mount is performed from inside the grind chamber. The presence of the portion of the dishwasher inlet in the grind chamber prevents the molding tool from reaching certain portions of the anti-vibration mount, thereby increasing molding complexity of the anti-vibration mount. Moreover, the presence of the dishwasher inlet inside the grind chamber also causes difficulty in the molding of the disposer body.